Janice Dickinson flashed shoppers at an H&M store over the weekend and called a cashier “monkey brain,” a customer claims. Our spy at the LA outpost on Sunset Boulevard said the ex-supermodel, 56, didn’t bother to use a dressing room to try on leggings, “dropped her pants” and “wasn’t wearing underwear.” According to our source, Dickinson later yelled, “Listen, you monkey brain!” when she was annoyed with a cashier and loudly announced, “I’m a former supermodel.” Dickinson told us, “I did go to H&M because I’m collecting apparel for the people of Haiti. Of course I don’t use dressing rooms. There was no one in the store.” She clarified: “Any woman in their right mind in this economy wants to collect clothes for charitable purposes.” As for her lack of panties, she said, “The shopper needs glasses. I wear La Perla G-string nude and they were on me.” She said the “monkey brain” cashier is her friend “Brett” and denied calling herself a “former supermodel.” “There’s nothing former about me. I was at the top of the food chain. I coined the term.”